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Topic: New Project: 1940's 'Amprosound' Projector |
Aaron Jennings
From:
Montana, USA
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Posted 9 Sep 2015 2:33 pm |
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Hey everybody!
I'd been lusting after some of those Electar and similar amplifiers of old, and ended up impulse buying a new project online. I had heard these cabinets/speakers were desirable, and noticed this had a built in audio amplifier!
I got it in the mail yesterday, it's obviously been well preserved, and came with all the maintenance equipment (including an RCA replacement tube!).
It's an Ampro 'Premier 30' 'Amprosound' projector. I've been looking at the available schematics and other information on the internet, and I'm pretty sure I've found the correct one, here:
http://www.film-tech.com/warehouse/manuals/AMPRO3.pdf (schematic at the end)
My vision, is to take the amplification circuit out of the projector, and install it directly into the back of one of these speaker cabinets (contains 'Operadio' speaker..)
The manual describes the amplifier thusly:
75 watts 100-120 volts 50-60 Cycle (AC Only)
5z4 Rectifier tube
6v6 Power Output tubes (2 required)
6N7 Driver & Oscillator tube
6J7 Voltage Amplifier tube
...all I know is that it sounds GREAT!
This is my first real tube-amp project - I'm hoping a transplant won't be terribly complex. I'm a complete novice with a book on how to service tube amps.
If anybody here has experience with projects like this, and wants to point out some of the common pitfalls - I'd be really appreciative!
Especially if there's any chance of live voltage on the inside.. |
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Bud Angelotti
From:
Larryville, NJ, USA
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Posted 9 Sep 2015 6:52 pm
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Too bad you have to take that beautiful piece apart and use it for another purpose. That machine is like a little brother to the old western electric sound system that can play "talkies". Reuse, make-do, or do without.
Really neat piece!
Is the sprocket 16 or 15, you outa find out cause if it's 15, it might be worth some serious dough to a film collector or historian.
It's portable too!
That was real hot tech in it's day. 
_________________
Just 'cause I look stupid, don't mean I'm not. |
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Craig Baker
From:
Eatonton, Georgia, USA - R.I.P.
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Posted 9 Sep 2015 8:39 pm
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Ampro is a grand old name that's been around for a long time, and been re-created a few times as well. The name sprang up in the late 60 in the radio industry. In the early 70s I worked for Ampro (Alex Myer Products.) manufacturing consoles under their name as well as the RCA name.
Aaron, hopefully your amplifier will sound better than the Ampro I knew. Here's a photo. . .
There was Ampro computer equipment, and also an Ampro tape recorder, I was told it was the consumer version of Ampex. Maybe, maybe not.
Aaron, yours is a quality vintage amp. Hope you get lots of enjoyment from it. Let us know how it sounds.
Craig
_________________
"Make America Great Again". . . The Only Country With Dream After Its Name. |
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John Limbach
From:
Billings, Montana, USA
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Posted 10 Sep 2015 5:00 am
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Aaron:
Bring it over sometime. I work on that kind of stuff and I have a bench full of test equipment that you can use too. |
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Tim Whitlock
From:
Colorado, USA
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Posted 10 Sep 2015 6:34 am
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Those cabinets are just too cool for school. I had been eyeballing an identical Ampro cabinet on eBay with the idea of beefing up the speaker for use with my Dual Showman.
I would think a transplant would not be complex at all. It's more of a mechanical than an electrical project. You might consider building a separate cabinet for the amp to reside in rather than trying to alter the speaker cabs. I too have reservations about dismantling a rare, working vintage A/V setup and it would be ideal if all your modifications were reversible. |
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Aaron Jennings
From:
Montana, USA
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Posted 10 Sep 2015 7:38 am
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Thanks for the feedback everyone!
I also have some reservations about cannibalizing a complete, working machine. However, it seems to me that these (16mm) projectors are not too hard to find in working order. (The speaker cabs seem to command most of the price).
It comes up okay, but I think one of the tubes (or a cap?) is going. After about 10-15 minutes, it starts to hum quite loudly (which quickly escalates to a scream.)
I think the next step for me is to disassemble it, and start testing each component. I'm armed with a cheapo DMM, and a recently acquired emission tube tester (EICO).
I've got a ton of reading to do.
Looks like I'm not the only guy with this idea though. There's a couple of these circuits on ebay right now. Here's one that looks just like mine:
John, I'd love to come out sometime and visit! Let me think about the best way to make that work, and I'll get in touch! |
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